How to implement a UK postcode lookup in PHP?

You can implement a UK postcode lookup in PHP using cURL. Send a request to https://findaddress.io/API/ with your apiKey, house, and postcode. You can pass these as query parameters or via a POST request using application/x-www-form-urlencoded.

How do I find a UK address by postcode and house number?

To find a specific address, pass both the house number/name and the postcode to the findAddress.io API. For example: /API/?apiKey=KEY&house=10&postcode=SW1A2AA. If you only have the postcode, use 'NULL' for the house parameter to see all available addresses at that location.

Is there a simple REST API for UK address lookups?

Yes, findAddress.io provides a simple REST API that returns UK address data in JSON format. It supports authentication via query string (apiKey) or header (x-api-key) and works with any language that can make HTTP requests, including Python, Node.js, and jQuery.

How do I get latitude and longitude from a UK postcode?

Every successful findAddress.io API call returns 'latitude' and 'longitude' coordinates alongside the address data. This allows you to map the location or calculate distances immediately after the postcode lookup.

How to handle UK postcode search in a Laravel application?

In Laravel, use the Http facade: Http::get('https://findaddress.io/API/', ['apiKey' => 'YOUR_KEY', 'house' => '10', 'postcode' => 'SW1A2AA']). This returns a JSON response containing the full validated UK address.

What is the best getAddress.io alternative for developers?

findAddress.io is a leading getAddress.io alternative, offering a similar JSON structure but with simplified authentication (no referer whitelisting required) and more flexible GET/POST methods for UK address and postcode validation.

Documentation

Q: How can I get an address from a postcode using JavaScript?

To get an address from a postcode using JavaScript, use the Fetch API to make a GET request to findAddress.io. Example: fetch('https://findaddress.io/API/?apiKey=YOUR_API_KEY&house=10&postcode=SW1A2AA'). The API returns a JSON object with a structured expandedAddress including street, town, and county.

Initial setup

If you're already here, then we assume you have already signed up to one of our postcode lookup plans. If not, head over to plans and signup. This is a quick process — login into PayPal after choosing your plan, accept the billing agreement (you won't be charged for 14 days if signing up to our trial), and you'll be directed to your account where you can get your API key.

Authentication

Update (16-02-2026): Authorised sites / referrer checks are now deprecated and no longer required in any circumstance. Existing integrations using referrer headers will continue to work, but you can safely remove them.

You only need an API key to use the API. You can pass your API key in one of two ways:

Query string: apiKey (recommended for simple tests / quick implementations)
Header: x-api-key (recommended for server-side usage)

Making a call

The API supports both GET and POST. You will need your API key, a postcode, and a house value.

GET (query string)

Use the endpoint below with apiKey, house, and postcode as query parameters:

https://findaddress.io/API/?apiKey=YOUR_API_KEY&house=10&postcode=SW1A2AA

We recommend removing spaces from the postcode (e.g. SW1A2AA). If you include spaces, URL-encode them (e.g. SW1A%202AA) or replace with +.

POST (form or JSON body)

Send the same keys via POST to:

https://findaddress.io/API/

Supported keys:

apiKey (string)
house (string)
postcode (string)

Important: The API reads parameters using $_REQUEST. For POST requests, the most compatible format is application/x-www-form-urlencoded (form encoded). JSON bodies are supported if you have enabled JSON parsing server-side.

Header authentication (still supported)

If you prefer, you can continue to pass your API key via the standard header:

x-api-key: YOUR_API_KEY

When using header auth, you can still pass house and postcode via query string or POST body.

Example cURL (GET + query string)

curl -X GET "https://findaddress.io/API/?apiKey=YOUR_API_KEY&house=10&postcode=SW1A2AA"

Example cURL (GET + header)

curl -X GET "https://findaddress.io/API/?house=10&postcode=SW1A2AA" \
  -H "x-api-key: YOUR_API_KEY"

Example cURL (POST + form encoded)

curl -X POST "https://findaddress.io/API/" \
  -H "content-type: application/x-www-form-urlencoded" \
  --data "apiKey=YOUR_API_KEY&house=10&postcode=SW1A2AA"

Example cURL (POST + JSON body)

curl -X POST "https://findaddress.io/API/" \
  -H "content-type: application/json" \
  -d '{"apiKey":"YOUR_API_KEY","house":"10","postcode":"SW1A2AA"}'

Call responses

All responses are returned as JSON and include your remaining daily calls and remaining monthly credits, plus a result and status code.

Successful response

{
"result": "Success",
"callsRemaining": 2928,
"creditsRemaining": 74928,
"latitude": "51.503540",
"longitude": "-0.127695",
"expandedAddress": {
"house": "10",
"street": "Downing street",
"locality": "",
"town": "London",
"district": "Greater london",
"county": "London",
"pCode": "SW1A 2AA"
},
"csvAddress": "10,Downing street,,London,Greater london,London,SW1A 2AA",
"statusCode": "200"
}

Partial Match

Partial matches are returned when we have no direct match in our primary dataset, but our redundancies provide an approximate match (for example, new developments or incomplete street data). Missing fields will be returned as blank.

{
"result": "Partial match",
"callsRemaining": 2928,
"creditsRemaining": 74928,
"latitude": "",
"longitude": "",
"expandedAddress": {
"house": "10",
"street": "",
"locality": "",
"town": "London",
"district": "Greater london",
"county": "London",
"pCode": "SW1A"
},
"csvAddress": "10,Downing street,,London,Greater london,London,SW1A",
"statusCode": "200"
}

Invalid postcode

This response is returned when the postcode is not valid. We validate against multiple sources (including defunct postcodes) and maintain redundancies for coverage. Ensure your postcode is correct and URL-safe (remove spaces or URL-encode them).

{
"result": "Failure",
"callsRemaining": "2913",
"creditsRemaining": "74913",
"errorMsg": "Postal Code Not Valid",
"statusCode": "400"
}

Unauthorised access

This response is returned when your API key is missing/invalid or you do not have an active subscription.

{
"result": "Failure",
"errorMsg": "Unauthorised access",
"statusCode": "401"
}

Exceeded limit responses

These responses are returned if you have exceeded your daily or monthly limits.

{
"result": "Failure",
"errorMsg": "You have exceeded your daily limit",
"statusCode": "429"
}

{
"result": "Failure",
"errorMsg": "You have exceeded your monthly limit",
"statusCode": "429"
}

Subscription lapsed

If your subscription is not renewed, access continues until your current billing period end date. After that you will receive:

{
"result": "Failure",
"errorMsg": "Your subscription ended on 15-02-2026",
"statusCode": "401"
}

Database error

If you receive this response, something has gone wrong at our end. Please contact us so we can investigate.

{
"result": "Failure",
"errorMsg": "Database Error #errNo. - Please contact support @
findaddress.io",
"statusCode": "500"
}

Code examples

Below are real-world UK address lookup API examples using PHP, JavaScript, Python, Laravel and cURL. Each example demonstrates how to validate a postcode and retrieve a complete UK address using findAddress.io.

PHP cURL GET UK Address Lookup API Example

$curl = curl_init();

$url = "https://findaddress.io/API/?apiKey=" . urlencode($apiKey) .
       "&house=" . urlencode($house) .
       "&postcode=" . urlencode(str_replace(' ', '', $postcode));

curl_setopt_array($curl, array(
  CURLOPT_URL => $url,
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => array(
    "content-type: application/json"
  ),
));

$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

PHP cURL GET Address API with API Key Header Example

$curl = curl_init();

$url = "https://findaddress.io/API/?house=" . urlencode($house) .
       "&postcode=" . urlencode(str_replace(' ', '', $postcode));

curl_setopt_array($curl, array(
  CURLOPT_URL => $url,
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => array(
    "content-type: application/json",
    "x-api-key: " . $apiKey
  ),
));

$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

PHP cURL POST Form Encoded UK Address Lookup API Example

<?php

$apiKey   = "YOUR_API_KEY";
$house    = "10";
$postcode = "SW1A2AA";

$ch = curl_init();

curl_setopt_array($ch, [
    CURLOPT_URL => "https://findaddress.io/API/",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST => true,
    CURLOPT_POSTFIELDS => http_build_query([
        "apiKey"   => $apiKey,
        "house"    => $house,
        "postcode" => $postcode
    ]),
    CURLOPT_HTTPHEADER => [
        "Content-Type: application/x-www-form-urlencoded"
    ],
    CURLOPT_TIMEOUT => 30
]);

$response = curl_exec($ch);

if (curl_errno($ch)) {
    echo "cURL Error: " . curl_error($ch);
} else {
    echo $response;
}

curl_close($ch);
?>

PHP cURL POST JSON Address Lookup API Example

<?php

$data = [
    "apiKey"   => "YOUR_API_KEY",
    "house"    => "10",
    "postcode" => "SW1A2AA"
];

$ch = curl_init();

curl_setopt_array($ch, [
    CURLOPT_URL => "https://findaddress.io/API/",
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST => true,
    CURLOPT_POSTFIELDS => json_encode($data),
    CURLOPT_HTTPHEADER => [
        "Content-Type: application/json"
    ],
    CURLOPT_TIMEOUT => 30
]);

$response = curl_exec($ch);
echo $response;

curl_close($ch);
?>

JavaScript Fetch GET Address Lookup API Example

const apiKey = "YOUR_API_KEY";
const house = "10";
const postcode = "SW1A2AA";

fetch(`https://findaddress.io/API/?apiKey=${encodeURIComponent(apiKey)}&house=${encodeURIComponent(house)}&postcode=${encodeURIComponent(postcode)}`, {
  method: "GET"
})
.then(res => res.json())
.then(data => console.log(data))
.catch(err => console.error(err));

JavaScript Fetch POST Address Lookup API Example (Form Encoded)

const body = new URLSearchParams();
body.append("apiKey", "YOUR_API_KEY");
body.append("house", "10");
body.append("postcode", "SW1A2AA");

fetch("https://findaddress.io/API/", {
  method: "POST",
  headers: { "content-type": "application/x-www-form-urlencoded;charset=UTF-8" },
  body: body.toString()
})
.then(res => res.json())
.then(data => console.log(data))
.catch(err => console.error(err));

jQuery Address Lookup API Example (UK Postcode)

$.ajax({
  url: "https://findaddress.io/API/",
  method: "POST",
  data: {
    apiKey: "YOUR_API_KEY",
    house: "10",
    postcode: "SW1A2AA"
  }
}).done(function(resp){
  console.log(resp);
});

Axios UK Address Lookup API Example

const axios = require("axios");

axios.get("https://findaddress.io/API/", {
  params: {
    apiKey: "YOUR_API_KEY",
    house: "10",
    postcode: "SW1A2AA"
  }
})
.then(response => console.log(response.data))
.catch(error => console.error(error));

Python Requests Address Lookup API Example

import requests

url = "https://findaddress.io/API/"
params = {"apiKey": "YOUR_API_KEY", "house": "10", "postcode": "SW1A2AA"}

response = requests.get(url, params=params)
print(response.json())

Laravel HTTP Client Address Lookup API Example (Form Encoded)

use Illuminate\Support\Facades\Http;

$response = Http::asForm()->post('https://findaddress.io/API/', [
    'apiKey' => 'YOUR_API_KEY',
    'house' => '10',
    'postcode' => 'SW1A2AA',
]);

return $response->json();

cURL Shell UK Address Lookup API Example

curl -X GET "https://findaddress.io/API/?apiKey=YOUR_API_KEY&house=10&postcode=SW1A2AA"